Flood Spreading

Abstract

Due to the variation and complexity of land use, population and social-economic activities, and climate change, stormwater runoff management is a complex task in recent years. During the last century, climate change leads to changes in precipitation and temperature patterns. High-intensity rainfall in some of the arid and semiarid regions and seasonal extreme drought in humid areas are a consequence of climate change. The bimodal and high rainfall should lead to infrequent floods that can be extremely harmful. This unconventional condition is worth investigating in the arid and semiarid areas, where not only the quantity of rainfall is insignificant, but the distribution of rainfall in time and space is also irregular. The rainfall regime in such areas is characterized by low and unpredictable precipitation, often concentrated into a few times, creating humid conditions in the soil for a short period and over a limited area. The high-intensity and short-duration convective rainfall causes extensive overland flow. This overland flow, concentrated by the topography, converges on the result that a flood flows. In this area, the floods are infrequent but extremely damaging, and the threat from floods to lives and infrastructure is increasing due to climate change. Also, there are many problematic effects of flooding on human economic activities; however, floods can be viewed as benefits especially in the arid and semiarid areas, where water shortage is more serious. Rainwater harvesting is a suitable method that could decrease evapotranspiration, increase groundwater recharge, and decrease flood hazards. Floodwater spreading is a suitable water harvesting method for flood management and reusing of the sediment, which is usually wasted via floods, in the case of suitable site selection.